Hoses have been reinforced in various ways for many different applications. These reinforcements can include braids on the outside of hoses for abrasion resistance, braids for mechanical reinforcement against the hose's internal pressure load (such as that created by a fluid under high pressure), coils or convolutions for crush resistance (i.e., kinking or transverse compression), and coils or braids for strain relief near junctions, among others. Generally, these reinforcements are intended to protect the hose from internal pressures, external radial loads (crushing, bending, or kinking) and tensile forces (anti-stretch). In other instances, metallic tubes such as those comprised of nickel-titanium alloy (nitinol) have been used, but these tubes lack the flexibility desired for certain applications and must be laser cut for the specific uses.
Polymer hoses are flexible and can be easily dimensioned for medical implant applications; however, the reinforcements described above are not meant to guard against longitudinal compression loads on the hose. This longitudinal compression may cause compressive creep of the hose, which can present challenges in applications requiring high-accuracy that is maintained over time such as a long-term medical implant. For example, a hose or tube may be used to precisely position a medical device in a patient. The hose can be implanted over a separate flexible guide shaft and anchored at one end. The medical device may be attached to the hose at the other end. Loads on the medical device (e.g., heart beats of the patient) can cause axially compressive loading of the hose, which can lead to compressive creep of the hose and lead to loss of accurate positioning of the medical device within the patient. Tests have shown that methods of reinforcing with coil or braid alone do not provide significant creep resistance when loaded in a manner representative of this application.
Therefore, devices, systems, apparatus, and methods are needed that overcome challenges in the art. Specifically, devices, systems, apparatus, and methods are needed that resist compressive creep of a hose caused by axially compressive loads.